Xling, a pocket demon

This is a little tamagotchi-like toy I've created for my wife. I used to think that this is how a modern Tamagotchi could look like initially. However, it can also be used as a battery-powered DIY platform to experiment with FreeRTOS and graphics.

Specifications

• 35x47mm board
• Monochrome OLED 128x64px
• Low energy consumption (~20mA @ active, 0.75mA @ sleep)
• Hand-soldering friendly (TQFP-44 0.8mm pitch, smallest is 0603)
• 3D-printable case
• Open Source Hardware/Firmware

Hardware

• ATmega1284P 8-bit AVR MCU with 128 KiB flash and 16 KiB SRAM
• SH1106G display controller
• MCP73831 charge controller
• AP3401 DC-DC buck converter
• 400mAh 3.7V Li-Po battery (~26h @ active, ~30 days @ sleep)
• Load-sharing circuit (can be powered by USB or battery, like a smartphone)
• KiCad 5.1.0 project for schematic and board designs
• Released under CERN-OHL-W v2 (Rev. 4) and CC-BY-SA (before Rev. 4)

Software

Please, note that the software part of the project isn't finished yet!

• Shows a frame time, energy left and a battery charged status
• Animation with Exy-in-the-bottle, a "personal daemon"
• Programmed in C99 using the FreeRTOS kernel modified for ATmega1284P
• There are three tasks only: Display, Battery Monitor and Sleep Mode
• Released under GNU GPLv3+

Website and Contact

Hackaday.io project: https://hackaday.io/project/165726-xling
Email: dsl AT mcusim DOT org
Dmitry Salychev